Pairings
Pairings are automation primitives that connect two resources, which are referred to as the source and destination. Changes observed to the source resource can be automatically applied to the destination resource, and vise-versa.
In forward propagation, changes observed to the source are applied to the destination. In reverse propagation, changes observed to the destination are applied to the source. Both propagation modes can be enabled simultaneously, allowing for resource value synchronization.
In addition to basic value mirroring, two custom transforms can be specified: a forward transform that is applied to changes from the source to the destination, and a reverse transform that is applied to changes from the destination to the source. These transforms are written using the expression language outlined in (#sae).
All pairings implement the AutomationPairing trait, described in (#trait-automation-pairing).